Date: Tue, 30 Sep 2008 14:19:52 +1000 From: Andrew Snow <andrew@modulus.org> To: freebsd-stable@freebsd.org Subject: Re: UNEXPECTED SOFT UPDATE INCONSISTENCY; RUN fsck MANUALLY Message-ID: <48E1A8E8.3090904@modulus.org> In-Reply-To: <20080930041215.GH86326@dan.emsphone.com> References: <249873145.20080926213341@takeda.tk> <20080927051413.GA42700@icarus.home.lan> <765067435.20080926223557@takeda.tk> <20080927064417.GA43638@icarus.home.lan> <588787159.20080927003750@takeda.tk> <5f67a8c40809282030l7888d942q548d570cd0b33be9@mail.gmail.com> <20080929040025.GA97332@icarus.home.lan> <48E080C0.9070103@modulus.org> <5f67a8c40809290809j58639df8ka65184151161cab6@mail.gmail.com> <48E183A2.8000209@modulus.org> <20080930041215.GH86326@dan.emsphone.com>
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Dan Nelson wrote: > That'd be handy, but at least on my system the data prefetcher isn't > really called often enough to make a difference either way (assuming > the counts are accurate). Metadata prefetch is a big win, however. arcstats.prefetch_data_hits: 4538242 (13%) arcstats.prefetch_data_misses: 29298997 arcstats.prefetch_metadata_hits: 593799808 (96%) arcstats.prefetch_metadata_misses: 21582847 You are much luckier than me. For obvious reasons, I would like to completely disable data prefetch but leave on metadata prefetch. I believe it would speed up the filesystem plus save RAM (less wasted use of ARC). But especially desktop systems would not need to waste space on such aggressive prefetching. - Andrew
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